Lamp circuit



Sept. 19, 1933. R TRUCKSESS 1,927,474

LAMP CIRCUIT Filed July 5, 1951 Invenfor Patented Sept. 19, 1933 UNITEDSTATES PATENT OFFICE 1 Claim.

This invention appertains to new and useful improvements in the art ofmotion picture projection, and the principal object of the invention isto provide means whereby the usual revolving l shutter and itsconsequent flicker on the screen is eliminated.

Another important object of the invention is to provide means forproducing a clear, life-like reproduction of human intelligence on ascreen without the usual iiickering.

Other important objects and advantages of the invention will becomeapparent to the reader of the following specification.

In the drawing:-

The gure represents a diagrammatic view disclosing the novel system.

Referring to the drawing wherein like numerals designate like parts, itcan be seen that numeral 5 represents the usual upper fllm reel andnumeral 6 represents the lowerdrive reel for the film strip 7. A motor 8is used to drive the lower reel 6 by way of the shaft 9 and this shaft 9is equipped with a pulley 10. Numeral 11 generally refers to a lightsource which includes in its construction a cathode, anode, and grid.

The container 12 of this tube is to enclose a volume of mercury vapor.Numeral 13 represents a current supply circuit which includes theresistance 14 and inductance 15 in series with the plate 16, andshunting this is the condenser 17. The opposite side of the circuit 13is in connection with the lament 18 and numeral 19 represents a batteryor other source of current for the lament 18. Numeral 20 represents theswitching circuit which includes the source of current 21 for the grid22.

In this switching circuit 20 is the circuit breaker 23 which may be ofany suitable type but preferably of a type that can be operated by a cam23'. This cam 23' is driven by the shaft 24 which has a pulley 25thereon, and as is clearly shown in Fig. 1, a belt or any other endlessdrive element 26 is trained over these pulleys 10 and 25, so that therotation of the shaft 9 will drive the shaft 24 at the same rate ofspeed. Thus, each time a picture on the lm 'I arrives in focus with thetube 11 the lenses 27, the cam 23 will break the circuit 20 so that thecharge on the condenser 1'7 can dissipate in the mercury arc between theanode 16 and filament 18. In this type of tube, the lament serves onlyas a means to excite the tube and does not furnish any light, themercury arc between the filament and anode is what causes the light andthis arc is instantaneously created and shut off under control of thegrid 22.

In other words, the very moment that the circuit 20 is broken, the arcis created in the gaseous container 12 and as soon as the charge is shutoff, this arc will disappear.

The purpose of the resistance in the current supply circuit is to limitthe current that will flow from this circuit during the time that thelamp is furnishing light. The purpose of the inductance in this samecircuit is to control the speed at which the condenser discharges intothe tube, or, in other Words, to control the time intensity of the lightemitted from the lamp.

With such a system, the usual conventional shutter is completelyeliminated with the resultant icker on the screen.

The excitation in mechanical coupling of this generator to the machinemay be done in many ways known to the art.

While the foregoing specification sets forth the invention in specificterms, it is to be understood that numerous changes in the shape, sizeand materials may be resorted to without departing from the spirit andscope of the invention as claimed hereinafter.

Having thus described my invention, what I claim as new is:-

A switching system of the character described comprising a lamp havingan anode, a cathode and a grid; a current supply circuit interrupted bythe said cathode and anode, a capacity across the anode and cathode, anda breaker circuit interrupted by the grid and cathode and including asource of current.

ROBERT TRUcKsEss.

